1. Field of the Invention
This invention relates to apparatus for positioning rig equipment in a desired position on a drilling rig floor. With further specificity, this invention relates to apparatus designed to be removably mounted on a drilling rig floor, which provides means for holding drill pipe tongs at a desired horizontal displacement from the center of the rig floor, by latch means that accept and releasably hold a catch piece affixed to the drill pipe tongs.
2. Description of the Related Art
Drilling rigs for drilling oil and gas wells usually employ at least two sets of drill pipe "tongs", or large wrenches, to make up and break out the threaded connections which join individual joints of pipe into long "strings". These tongs are suspended at a desired height above the rig floor by a cable which passes over a pulley mounted near the top of the derrick or mast of the rig. The end of the cable opposite the tongs connects to a counterweight, adjusted to be nearly the same weight as the drill pipe tongs, so that the tongs may be easily raised and lowered to a desired height. The pulley is generally placed nearly overhead the center of the rig floor, and the weight of the tongs creates a pendulum effect tending to always swing the tongs toward the center of the rig floor. As the tongs are usually being used on connections on drill pipe or other drill string components that are held in slips in the center of the rig floor, the tendency of the tongs to swing toward the center of the rig floor is often advantageous. However, for a number of tasks during the drilling of a well, it is desirable to pull the tongs away from the center of the rig floor, so that free and uninhibited access to the central rig floor area can be had. A problem arises in securing the tongs at a desired horizontal displacement away from the center of the rig floor, while permitting easy release of the tongs when desired.
Past methods generally involved tying the tongs off to stanchions or structural members of the rig, often with a knotted rope or a chain draped through a hook welded to the tongs. This method presents a number of drawbacks. First, the rig worker must push the tongs to the desired tie off point, generally using both hands, then remove one hand from the tongs in order to lift and place the rope or chain through the hook. The process must be reversed in order to free the tongs. The necessary removal of one hand from the tongs to place or remove the rope or chain greatly decreases the rig worker's control over the tongs.
With increasing emphasis on safety and efficiency in rig operations, the old method of tying off tongs has become increasingly unacceptable. Often, tongs would come loose from their ties and swing toward the center of the rig floor. The great weight and inertia of the free-swinging tongs striking rig workers in their backs or other parts of the body, and having parts of their body, especially fingers and hands, "sandwiched" between a swinging tong and a section of drill pipe, has caused many injuries. Due to the inconvenience in tying off tongs away from the well bore, rig workers would often simply let the tongs hang free, and push them just far enough out of the way to perform their desired tasks (without tying them off), while always keeping a look out for the tongs tending to swing back toward the center of the rig floor and possibly strike them.
The related art shows no apparatus, readily adapted to existing rig equipment, which provides a convenient, positive retaining means for holding tongs at a desired horizontal displacement away from the center of the rig floor, while permitting easy release when desired to use the tongs at the center of the rig floor.
It is therefore an object of the present invention to provide an apparatus for positive retention of rig tongs and other rig equipment at a desired horizontal displacement away from the center of the rig floor. It is a further object of the present invention to provide apparatus which permits engagement and retention of the tongs by simply guiding a catch piece connected to the tongs into a latch, the latch comprising a jaw and retainer arm, so that the catch piece is caught behind the retainer arm and positively retained. Yet another object is to provide apparatus adapted to easy installation on a drilling rig and incorporation with existing equipment, and that is easily removed if not needed or when the drilling rig is being moved from one location to another. Still further objects are to provide apparatus that permits easy height and horizontal position adjustments, that requires only simple modifications to existing rig equipment, that greatly increases rig safety by holding tongs positively away from the center of the rig floor, and that has such ease of use that rig workers will voluntarily and willingly use it. Finally, an object of the present invention is to provide an apparatus that is simple and inexpensive to fabricate and install on virtually any type of drilling rig.